Multi Root Vegetable Soup With Mace

Name: Multi Root Vegetable Soup With Mace
Ingredients: 2 tbsp olive oil; 1 tbsp butter; A few twigs lemon thyme; 1 tsp ground coriander; 1 small yellow onion; 1 x leek, white part only, chopped; 2 x garlic cloves; Half of one butternut squash; 2 x turnips, peeled and diced; 2 x parsnips, peeled and diced; 1 x sweet potato; 2 x carrots, peeled and diced; 1 x kaffir lime leaf; 3 small pieces of mace; 1 tsp brown sugar; 4 cup chicken stock (more if needed); Sea salt and pepper; Heavy cream, to taste; Fresh parsley, chopped, to serve